Sensitivity comparison of Rydberg atom-based radio frequency electric field detection: Ionization current versus optical readout

We investigate a technique for detecting radio frequency (RF) electric fields in a cesium (Cs) vapor cell at room temperature by collecting charges from ionized Rydberg atoms and compare its performance with the established method of electromagnetically induced transparency (EIT). By applying a known RF field, we measure the response from both the electrical (ionization current-based) and optical (EIT-based) readouts. The ionization current-based method yields a sensitivity of 22 μ V m−1 Hz−1/2, while the EIT-based method achieves 3.7 μ V m−1 Hz−1/2. The sensitivity of the ionization current-based method is limited by the 2.2 k Ω resistance between the collection electrodes, attributed to a thin Cs film on the inner surfaces of the vapor cell. Controlling or eliminating the Cs layer can significantly improve the sensitivity of this ionization approach.